In general, when coloured paving is applied in parks or pavements, binder compositions which can be coloured by the addition of pigments and the like are used. Such binder compositions for coloured paving include for example those wherein a petroleum resin and/or a thermoplastic elastomer and a petroleum-based softener are compounded in defined proportions, and antioxidants and the like are added if necessary.
Since binder compositions for coloured paving are usually exposed outside for long periods, it is necessary to suppress deterioration due to water, heat, oil and ultraviolet radiation to the minimum. Thus, in order to improve weather resistance, binder compositions for coloured paving have been proposed (see for example JP 2001-172469 and JP 2001-329117) wherein, as the petroleum resin and thermoplastic elastomer, respectively, hydrogenated petroleum resin and hydrogenated thermoplastic elastomer in which the double bonds in the molecule have been decreased by addition of hydrogen are used. Further, binder compositions for coloured paving have also been proposed (see for example JP 2002-206047) wherein, together with the use of the aforesaid hydrogenated petroleum resin and hydrogenated thermoplastic elastomer, the softener is changed from a petroleum solvent-extracted oil to a petroleum-based lubricating oil of low aromatics and double bond content.
On the other hand, there are also binder compositions for coloured paving which take account of effects on the environment and on the human body (see for example JP 2003-301111 and JP 2005-256450). In the binder composition according to JP 2003-301111, a petroleum-based heavy oil wherein the polycyclic aromatic hydrocarbon content has been decreased to 3 weight % or less, and the aromatics content to 15 weight % or less is used as the softener. Further, in the binder composition according to JP 2005-256450, a petroleum aromatic hydrocarbon oil wherein the polycyclic aromatic hydrocarbon content has been decreased to less than 3 weight % is used as the softener.
However, as described below, there are problems with the aforesaid previous technology. Although studies have been made of the weather resistance, durability and colour of the coloured paving binder compositions according to the prior art, their application properties have not been considered. For example, in order to improve their service durability, it is desirable if the viscosity of the binder composition is higher, however in that case the viscosity during application also becomes higher, mixing with the pigment and aggregate may become incomplete, and the flatness of the paved surface may decrease. On the other hand, if the viscosity of the binder composition is decreased in order to improve its application properties, its strength decreases, and loss of aggregate, rut formation and the like occur. Because of this, there are problems with previous coloured paving binder compositions in that it is not possible to have both the durability and the application properties satisfactory.